1. Field of the Invention
The invention relates to a control configuration for an occupant protection system for side collision protection in a vehicle.
From U.S. Pat. No. 5,544,915, a control configuration for an occupant protection system for side collision protection in a vehicle is known which includes one transverse acceleration pickup disposed in the left half of the vehicle, one transverse acceleration pickup disposed in the right half of the vehicle, and one transverse acceleration pickup disposed centrally in the vehicle. The signals furnished by the transverse acceleration pickups are each compared with threshold values. If the threshold values are exceeded by the respective signals, the side air bags, for instance, are tripped.
A control configuration for an occupant protection system for front-end collision protection is disclosed in German Utility Model DE 90 01 803. The occupant protection system is tripped only when the signal, furnished by an electronic acceleration sensor and evaluated in an evaluation device, indicates a severe accident calling for tripping of the airbag and at the same time a mechanical acceleration switch, also known as a safeguard sensor because of its protective function, furnishes an enable signal.
A mechanical acceleration switch of this kind serves to protect the occupants from faulty tripping of the airbag. If it did not exist, a defective electronic acceleration sensor or a defective evaluation device could furnish a control signal and cause the airbag to be tripped. Faulty tripping leads to major repair costs. Furthermore, the health and safety of the occupant can suffer, for instance from the noise generated when the airbag is inflated. In addition, an unexpected inflation of the airbag can make the driver react in an uncontrolled way and can cause an accident, for instance.
The mechanical acceleration switch does not require an energy supply the way an electrical acceleration sensor does. As a rule, it has a magnetic seismic mass, which is deflected by the influence of an acceleration, and which after a defined traversed distance actuates a magnetically controllable switch. The acceleration-dependent response threshold of the mechanical acceleration switch is purposefully set relatively low, so that the acceleration switch in an accident will generate a relatively long-lasting enable signal at a relatively early time, thus specifying a time slot for the actual control signal furnished by the evaluation device.
Since this kind of mechanical acceleration switch cannot be tested, or can be tested only at major effort and expense, as a protection configuration for the control configuration of an occupant protection system, it is proposed in Published, Non-Prosecuted German Patent Application DE 40 16 644 A1 that the mechanical acceleration switch be replaced with a second electronic acceleration sensor and a protection circuit. The analog acceleration signal of the further electronic acceleration sensor is integrated with the analog protection circuit and compared with a threshold value. If the threshold value is exceeded by the integrated acceleration signal, an enable signal is furnished.
From Published, Non-Prosecuted German Patent Application DE 44 03 502 A1, a control configuration is known in which a mechanical acceleration switch, embodied as a safeguard sensor, is replaced with an electronic acceleration sensor and a protection circuit. With a protection configuration embodied in this way, the behavior of a mechanical acceleration switch, especially a "ball-in-tube sensor" known from U.S. Pat. No. 4,329,549, is supposed to be simulated. To that end, a constant acceleration value is subtracted from the acceleration signal furnished by the acceleration sensor, in order to simulate a prestressing of a fictitious seismic mass of a mechanical acceleration switch. Under the influence of the acceleration picked up by the electronic acceleration sensor, the fictitious seismic mass of the simulated acceleration switch is deflected and, if a threshold value is exceeded, furnishes an enable signal. Accordingly, to simulate the acceleration switch, the measured acceleration signal, minus the acceleration value that represents the prestressing, is integrated into the protection circuit and compared with a threshold value.